Surplus ammo can be unreliable. While your storage precautions may be impeccable, you have no way of knowledge how it was treated in the decades before you received it. I've got some 8x56R from pre-WWII Nazi Germany that goes BANG with 100% reliability, and I have some Turkish 8mm Mauser from (I think) 1928 that is prone to hangfires.
That being said, with a 90% failure rate, I'd contact OGC and see if they've had other reports of similar performance. Worst case scenario, disassemble the cartridges for their components then reload them, or sell them cheap to a reloader.